I think it's pretty clear that Jennifer's actions wouldn't be prosecutable in a criminal court. But I do think it's possible that there's a case to be made in a civil suit. Given the circumstances leading up to and surrounding that encounter on the stairs, a jury might find Jennifer at least partially responsible in a "wrongful death" action -- leading her to have to pay damages but not go to jail. The burden of proof is quite different in civil courts. Of course, in filing a civil suit, Nicole would open herself up to public scrutiny of her own questionable and unstable behavior during that same time period. Fingers would be pointed at EJ, Daniel, and others as well.

So we're back to no one looking good or rootable in this whole thing. Maybe that's realistic, but it's not entertaining. As others have mentioned, there are so many other ways the writers could have chosen to go.